1. Field of the Invention
The present invention relates to photochromic compounds, particularly to photochromic substituted naphthopyran compounds, and more particularly to photochromic substituted naphthopyran compounds which display reduced film fatigue after exposure to visible light because of the selection of substituents on the naphthopyran.
2. Background of the Art
In recent years, photochromic plastic materials, particularly plastic materials for optical applications, have been the subject of considerable attention. In particular, photochromic ophthalmic plastic lenses have been investigated because of the weight advantage they offer, vis-a-vis, glass lenses. Moreover, photochromic transparencies for vehicles, such as cars and airplanes, have been of interest because of the potential safety features that such transparencies offer. When exposed to electromagnetic radiation containing ultraviolet rays, such as the ultraviolet radiation in sunlight or the light of a mercury lamp, many photochromic compounds exhibit a reversible change in color. When the ultraviolet radiation is discontinued, such a photochromic compound will return to its original color or colorless state.
Various classes of photochromic compounds have been synthesized and suggested for use in applications in which a sunlight-induced reversible color change or darkening is desired. U.S. Pat. No. 3,567,605 (Becker) describes a series of pyran derivatives, including certain benzopyrans and naphthopyrans. These compounds are described as derivatives of chromene and are reported to undergo a color change, e.g., from colorless to yellow-orange, on irradiation by ultraviolet light at temperatures below about xe2x88x9230xc2x0 C. irradiation of the compounds with visible light or upon raising the temperature to above about 0xc2x0 C. is reported to reverse the coloration to a colorless state.
U.S. Pat. No.5,066,818 describes various 3,3-diaryl-3H-naphtho[2,1-b]pyrans as having desirable photochromic properties, i.e., high colorability and acceptable fade, for ophthalmic and other applications. Also disclosed by way of comparative example in the ""818 patent are the isomeric 2,2-diaryl-2H-naphtho[1,2-b]pyrans, which are reported to require unacceptably long periods of time to fade after activation.
U.S. Pat. No.3,627,690 describes photochromic 2,2-di-substituted-2H-naphtho[1,2-b]pyran compositions containing minor amounts of either a base or weak-to-moderate strength acid. The addition of either an acid or base to the naphthopyran composition is reported to increase the fade rate of the colored naphthopyrans, thereby making them useful in eye protection applications such as sunglasses. It is reported therein further that the fade rate of 2H-naphtho[1,2-b]pyrans without the aforementioned additives ranges from several hours to many days to reach complete reversion.
U.S. Pat. No.4,818,096 discloses purple/blue coloring photochromic benzo- or naphthopyrans having at the position alpha to the oxygen of the pyran ring a phenyl group having a nitrogen containing substituent in the ortho or para positions. WO 96/14596 describes novel photochromic indeno-fused naphthopyran compounds, the 2,1-positions of the indeno group being fused to the f side of the naphthopyran.
U.S. Pat. No. 5,723,072 describes certain photochromic heterocyclic fused indenonaphthopyrans as novel photochromic heterocyclic fused indenonaphthopyran compounds. These compounds may be incorporated with polymeric organic host materials that contain or that are coated with such compounds and applied as photochromic coatings. As with most inventions within this field, the substituents allowed at the various positions ortho to the pyran oxygen are specifically defined and limited. The novel indenonaphtho[1,2-b]pyran compounds having a substituted or unsubstituted heterocyclic ring, the 2,3 or 3,2 positions of which are fused to the g, h, I, n, o or p side of the indenonaphthopyran, and certain substituents at the 3-position of the pyran ring. These compounds were asserted to demonstrate a bathochromic shift for the wavelength in the visible spectrum at which the maximum absorption of the activated (colored) form of the photochromic compound, i.e., the lambda max (Vis), occurs, thereby resulting in activated colors ranging from orange to blue/gray.
The present invention relates to naphthopyrans and particularly to novel substitution on the 3 position of naphthopyrans. It has been found that there are classes and types of substitution on the 3-position of a 2,1-b-naphthopyran (especially combinations of 3,3-substitution) which are novel or on the 2-position of the 1,2-b-naphthopyran (especially combinations of 2,2xe2x80x2-substituents). Some of these substitutions provide particularly desirable properties. In particular, the present invention relates to naphthopyrans wherein one 3-substituent (or 2-substituent for the 1,2-b-naphthopyran) comprises a phenyl group (including phenyl, substituted phenyl, biphenyl or substituted biphenyl) and the other 3-position (or 2-position for the 1,2-b-naphthopyran) substituent comprises a substituted phenyl group wherein the substituent is selected from the group consisting of anthranilyl, azepinyl, benzoxazolyl, diazepinyl, dioazlyl, imidazolidinyl, imidazolyl, imidazolinyl, indazolyl, indoleninyl, indolinyl, indolizinyl, indolyl, indoxazinyl, isobenzazolyl, isoindolyl, isooxazolyl, isooxazyl, isopyrroyl, isoquinolyl, isothiazolyl, morpholino, morpholinyl, oxadiazolyl, oxathiazolyl, oxathiazyl, oxathiolyl, oxatriazolyl, oxazolyl, piperazinyl, piperazinyl, piperazyl, piperidyl, purinyl, pyranopyrrolyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyrazyl, pyridazinyl, pyridazyl, pyridyl, pyrimidinyl, pyrimidyl, pyridenyl, pyrrolidinyl, pyrrolinyl, pyrroyl, quinolizinyl, quinuclidinyl, quinolyl, thiazolyl, triazolyl, and triazyl. Substitution at other positions on the naphthopyrans molecule may be liberally made according to the background knowledge of those with ordinary skill in the art. These substituted naphthopyrans are particularly useful as photochromic compounds within polymeric coatings and coating compositions used in the optical or ophthalmic art.